The present invention relates in general to ventilation of passenger vehicles, and, more specifically, to a pressure relief valve assembly for extracting air from a vehicular passenger compartment.
To obtain a quiet environment and to protect the interior passenger compartment of an automotive vehicle from outside elements, the compartment is substantially sealed from the atmosphere. During certain vehicle operating conditions, however, air pressure in the interior passenger compartment may exceed atmospheric pressure. This condition occurs routinely when a vehicle door is closed when entering or exiting the vehicle. If the interior is not vented to the atmosphere, the effort required to close the door may greatly increase, inconveniencing the operator of the vehicle. High internal pressures can also be created by operation of a blower in a climate control system or by the inrush of outside air when traveling at high speeds.
It is well known to provide a mechanism for equalizing the pressure between the interior compartment of an automobile and the atmosphere. Typically, a valve assembly is placed between the interior space and the outside of the vehicle in order to control an exhaust flow of air from the interior. One type of valve assembly known as a pressure relief valve or “air extractor” is typically connected, by way of one or more ducts, conduits, and/or vents, to the passenger compartment. The valve assembly allows air to be selectively expelled, discharged, or extracted from the vehicle passenger compartment, while substantially preventing air, gas, fumes, and/or other undesirable materials from entering into the passenger compartment. By eliminating and/or substantially reducing the pressure differentials, these pressure relief valve assemblies improve the performance of climate control systems, reduce door-closing efforts, minimize window frame deflection, and reduce noise within the passenger compartment of the vehicle.
A typical vehicle body air extractor is a passive valve that only permits air flow from a higher pressure vehicle interior to a lower pressure vehicle exterior. The aerodynamics of each particular vehicle affects the pressure appearing at various speeds at various locations along a vehicle exterior surface where the output of the air extractor valve may be mounted. The resulting pressures may limit the acceptable locations on the vehicle where the air extractor valve can be placed. In addition, heating, ventilation, air conditioning (HVAC) systems have required a sufficiently large main blower in order to produce sufficient air flow that will overcome air flow losses and exterior pressures to ensure a sufficient extraction of air from the vehicle interior space. However, as the main blower increases in size, an undesirable noise level may be produced by the blower.
In order to achieve a desired level for the door closing effort, a minimum size (i.e., flow area) has been required for the air extractor. An increase in air handling efficiency would be desirable since the overall size of the air extractor could be reduced.